Construction site operators are increasingly called upon to manage on-site stormwater which is a frequent on-site condition during construction and other earthwork projects. This demand is particularly strong in light of established and developing federal and state regulations intended to preserve and protect the quality of the nation's surface waters.
The Clean Water Act (formerly known as the Federal Water Pollution Control Act) is the primary federal legislation that protects the nation's surface waters. The Clean Water Act was amended to include the Water Quality Act of 1987, which addressed, in part, storm water discharge and required the Environmental Protection Agency (EPA) to develop a comprehensive phased program to regulate storm water discharge. The EPA is the governing authority in five states, namely, Massachusetts, New Hampshire, New Mexico, Idaho and Alaska. Other states have followed the national guidance adopting comprehensive state environmental protection acts which codify many of the federal environmental protection acts, including the federal Clean Water Act.
The three phases of the Clean Water Act have already been enacted. Phase I applied to stormwater discharges from medium and large municipal separate storm sewer systems and Phase II applied to small municipal separate storm sewer systems. Phase III, which took effect on Feb. 1, 2010, has an impact on nearly every construction and other development project. The non-numeric effluent limitations became effective on Feb. 1, 2010. Thereafter and over the next four years, the EPA is phasing in the specific numeric limitations and associated monitoring requirements applicable to large sites. Construction sites that disturb ten or more acres at one time were given four years to begin compliance. No later than Aug. 1, 2011, all sites that disturb twenty or more acres of land at one time are required to comply with the turbidity limitations. The EPA has estimated that the construction industry will spend $2 billion in new costs to comply with the new regulations.
Phase III of the Clean Water Act, among other things, establishes national clean water standards, known as effluent limitation guidelines, for the construction and development industry. One aspect of the upcoming federal guidelines is a numeric limitation on the amount of Nephelometric Turbidity Units (NTUs) which are allowable in stormwater discharge from construction sites. The turbidity limit is a measure of the quality of the water and it applies to active treatment systems which include polymer-assisted water clarification. Turbidity is measured in NTUs and is a very important parameter to monitor because the levels of NTUs in a body of water correlate to the clarity and quality of the water. Failure to comply with these new guidelines and water quality standards with respect to limits of NTUs in stormwater discharge from construction sites will carry significant penalties.
Construction activities (including other land-disturbing activities) that disturb between one and five acres or more, and smaller sites that are part of a larger, common plan of development are regulated under the National Pollution Discharge Elimination System (NPDES) stormwater program. Most states are authorized to implement the NPDES permit program, including the stormwater program. Under such programs, operators of regulated construction sites are required to develop and implement stormwater pollution prevention plans and to obtain permit coverage (the EPA refers to them as Construction General Permits, or CGP, and many states require similar permits) from an authorized state or from the EPA. The CGP covers any site one acre and above, including smaller sites that are part of a larger common plan of development or sale. The permit requires operators of the construction sites to use stormwater controls and develop stormwater pollution prevention plans to minimize the discharge of sediment and other pollutants associated with construction sites in stormwater runoff. Failure of a construction site operator to implement an adequate stormwater pollution prevention plan is a violation of the federal CGP, or similar state general permits as applicable, and can carry with it significant consequences including, for example, an enforcement action, massive civil and/or criminal penalties (including fines per day per violation), coverage termination, revocation and reissuance, or modifications or denial of a renewal application.
Accordingly, construction site operators are under increasing accountability for the implementation and maintenance of stormwater pollution prevention plans. As mentioned above, one of the technologies which has demonstrated the ability to achieve significant reduction in NTUs is polymer clarification. In this regard, presently, the Best Management Practice (BMP) utilized in the construction industry for the regulation and monitoring of stormwater is to install non-portable, non-self-contained filtration devices on the construction site. BMPs are directed at compliance with minimal state and/or federal regulations.
Typically, a water track or ditch is formed in the earth and bags containing a polymeric filter material are placed along the track. In an ideal application, as raw stormwater flows down the track, the raw water flows through and contacts the polymeric filter material and the filtering material cleans the water by filtering out undesirable impurities and contaminants. When the polymer mixes with the raw water, the polymer binds to the contaminants forming larger particles that should settle to the bottom or should be filtered out through other mechanical means, such as a jute yarn netting.
However, conditions on construction sites are rarely ideal. For example, harsh weather conditions can interfere with the filtration of raw water by the method described above. When the temperatures are at or below freezing, the water in the track or ditch also freezes preventing any water filtration from occurring. Because these non-portable filtration devices are not protected from such harsh environmental conditions, the filter track is susceptible to being covered by snow, ice and other debris, which can impair and even prevent water filtration from occurring.
And even if environmental conditions are ideal, the BMP non-portable filtration systems described above suffer from a number of other disadvantages. It is not uncommon that such filtration systems are improperly constructed so that optimal filtration cannot occur and, thus, the construction site operator could fail, for example, to meet minimal standards with respect to turbidity limits. Also, poorly maintained BMPs can result in significant quantities of sediment being discharged into the environment. Rarely do current BMPs facilitate optimal use of the filter material. This is true, for example, because of inadequate control of water flow through the filtering system.
Such non-portable filtration devices have other significant limitations with respect to the size of the construction site that it can accommodate. Typical non-portable, on-site filtration systems are problematic, for example, because often there is more than one area of the construction site which requires water filtration, so more than one non-portable filtration device must be installed for each distinct area. This, of course, is a costly endeavor and requires additional oversight and routine maintenance. Multiple, non-portable, on-site filtration device are also undesirable because they take up large areas of land, which can interfere with the construction activities. For example, a typical filtration ditch that can accommodate about 25 acres of land would likely include several stages, the first stage being about 8 feet wide, 6 feet deep and 10 feet long and ultimately graduating into a stage that is 8 feet wide, 2 feet deep and 30 feet long. The size of the non-portable filtration device continues to increase proportionately to the area of the construction, or other earth-moving, site and the concomitant amount of water requiring treatment.
The need to efficiently and effectively implement and maintain water pollution prevention programs is not limited to the construction and development industry. Operators of other types of earthwork projects where there is soil and environmental disturbance can benefit from the implementation and use of more effective and convenient ways to control on-site water pollution.
It would represent a significant improvement in the art to provide an apparatus and method to facilitate water filtration on-site, wherein such filtration apparatus would be mobile to accommodate any size construction site and the apparatus further would provide shelter from harsh environmental conditions to facilitate optimal water filtration, which would provide improved opportunity for exceeding applicable state and federal regulations.